Instructions and best practices for creating base images for StratusLab

The base installation of the OS can be done with a virtualisation software like VirtualBox, QEMU/KVM or VMware Player.

• Create a new VM and select an IDE bus for your HDD (very important for Windows).
• When installing your OS it is recommended to choose a simple HDD layout (for example only 1 partition for / and no swap).
• Choose DHCP method to get an IP address.

When installation has finished and VM has rebooted:

• Add programs and configurations you want.
• For Windows, install updates (recommended) and activate Windows Remote Desktop service (RDP server).
• For Linux, install openssh server.
• Edit /etc/fstab (it is recommended to use UUID except for the extra swap disk) to remove the cdrom line and add a line for a swap disk in /dev/sdb (/dev/hdb on SL550). For example: /dev/sdb swap swap defaults 0 0
• Remove /etc/udev/rules.d/70-persistent-net.rules and /etc/udev/rules.d/70-persistent-cd.rules.
• For SL and RHEL edit /etc/sysconfig/network-scripts/ifcfg-eth0 and remove the line with the mac address.

• Install StratusLab contextualisation package (RPM availlable at http://quattorsrv.lal.in2p3.fr/packages/stratuslab/stratuslab-one-context-0.0.1-0.20111215.110102.noarch.rpm). If you don't use a RPM package manager just extract the package in / and run /usr/bin/stratuslab-one-context-postinstall
• Edit /etc/stratuslab/stratuslab-one-context.cfg and set the cdrom block device to sr0 (hdd on SL550).
• Edit /etc/stratuslab/conf.d/01-password.context to activate random password and force root user to log in with a ssh key.
• Edit /etc/stratuslab/conf.d/99-quattor.context to activate configuration with Quattor.

• When configuration and contextualization are done, shutdown your VM.
• Convert the virtual HDD to raw disk format with that command:

vboxmanage internalcommands converttoraw disk.vdi disk.img

Be careful to have enough free disk space when you do that because it will deflate the disk image.

• Then compress it with:

cat disk.img | gzip > disq.img.gz

• Or convert it to qcow2 format:

qemu-img convert -c -f raw -O qcow2 disk.img disk.qcow2

You need of course qemu-img installed to do that. The conversion takes more time than gzip it's really worth it.

Now your disk image is ready. Serve hot, test it and enjoy!

• DHCP for the main network interface.
• Use a simple HDD layout, no need for swap partition.
• Delete all occurrences of the mac address of the network interface(s) (udev, sysconfig).
• Keep in mind that each instance is a clone. You can use contextualisation to specialize them.